Planetary Gear Lubrication Across a Rotation Gap
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Solution Overview
Problem
Planetary gear trains in aircraft engines face component breakage and wear due to misalignments, which are not adequately addressed by existing lubrication systems and flexible couplings, leading to increased maintenance costs and reduced engine efficiency.
Innovation Solution
A lubrication system for planetary gear trains that includes a stationary bearing with a lubricant input and a rotating bearing with conduits to deliver lubricant to distinct locations, ensuring effective lubrication across a rotation gap and accommodating misalignment, while a flexible coupling with a link and ball mechanism allows for torque transmission and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If gear train components are made larger to reduce wear and breakage, then component strength and wear resistance improve, but device compactness deteriorates
Solution Approach 1:
The bearing is divided into a stationary bearing and a rotating bearing, with the stationary bearing receiving lubricant and the rotating bearing delivering it through conduits. This segmentation allows the lubrication system to be distributed across the rotation gap, providing adequate lubrication without requiring larger gear components.
2Strength
If flexible couplings are used to reduce stresses from misalignment, then stress on gear components decreases, but coupling complexity and part count increase
Solution Approach 1:
A flexible coupling acts as an intermediary between the drive shaft and the sun gear, accommodating misalignment through its link and ball mechanism. This intermediary absorbs the misalignment stresses without requiring changes to the gear train components themselves.
3Reliability
If multiple lubrication points are provided across the rotation gap, then lubrication effectiveness improves, but system complexity increases
Solution Approach 1:
The rotating bearing is dynamically positioned within the stationary bearing, with conduits that rotate with it. This dynamic arrangement automatically provides lubrication to multiple distinct locations across the rotation gap as the rotating bearing turns, without requiring a complex multi-point lubrication system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The lubrication system reduces wear and breakage of gear components by ensuring consistent lubrication across the gear train, even with misalignment, and the flexible coupling provides necessary rigidity and strength for high-torque applications without increasing weight or cost.
Implementation Method 1
a lubrication system for planetary gear trains that includes a stationary bearing with a lubricant input and a rotating bearing with conduits to deliver lubricant to distinct locations
Data Source
AI summary
A gas turbine engine includes a fan shaft diving a fan having fan blades. A gear system includes a sun gear surrounded by a plurality of intermediate gears. A carrier at least partially supports the plurality of intermediate gears. A ring gear surrounds the plurality of intermediate gears. The sun gear is driven by a turbine. At least one fan shaft support bearing is located forward of the gear system. A coupling fixes the ring gear from rotation relative to an engine static structure. A lubrication system lubricates components across a rotation gap. The lubrication system includes a lubricant input. A stationary first bearing receives lubricant from the lubricant input and has a first race in which lubricant flows. A second bearing rotates within the first bearing. The second bearing has a first opening in registration with the first race such that lubricant may flow from the first race through the first opening into a first conduit.